Computing means



J. M. ANDERSON ET AL 2,538,226

COMPUTING MEANS Jan. 16, 1951 Filed Dec. 22, 1944 2 sheets-sheet 1 Jam 15, 1951 J. M. ANDERSON x-:T Al. 2,538,226

COMPUTING MEANS 2 Sheets-Sheet 2 Filed Dec. 22, 1944 .mt S mm um Patented Jan. 16, 1951 COMPUTING MEANS John M. Anderson and Frank M. Exner,- Minneapolis, and Raymond E. Haselberger, St. Paul,

Minn.,

assignors` to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation; of. Delaware Application December 22, 1944, Serial No. 569,336

13 Claims.

invention relates toA the field of aeronautica/t engineering,v and more speciiically to the: portionof that` lieldr dealing with instruments. for, indicating the drift angle and ground speed ot. a craft in the air. The invention comprises a novel variable resistor and a novel mechanical linkage".k in its broaderl aspects; however, ourl invention is, not limited to useA in this connection, but is of: broad' applicability whenever it desired to'y solve vector triangles., It is accordinglyV an object of' our invention to' provide a nevvand improved computing device.

It is an object oi our invention to provide a new and improved vector computer.

'It' is an` object ci ourv invention to provide new and improved means for solving triangles meyspeed oi the aircraft.

It is a further object of our invention to provide an instrument as described above which is. automatically corrected for change in the heading of the plane.

It is a still further object of our invention to provide an instrument asd'escribed' above which is automatically corrected for bothcha-nge. in the speed and changein. the headingA oi the craft.

It is, another ob-ject of our invention tojprovide y.a new and useful mechanical linkage..

It, is. yet another object of, our invention to provide a, novel and useful` means for' varying a resistance in accordance with three` independently varyingY factors.

It, i's still. another obiectl of our invention `to provide aV novel and'l useful means forvarying the resistance of a plurality of resistorsin accordance with changes in threev independentlyvarying factors..

Various other objects, `advantages, and features of novelty which rcharacterize our invem -use reference should be had to the subjoined drawing. whichv forms a furtherpart hereof,

2 and tothe accompanying descriptive matter, in which We have illustrated and described a preferred embodiment` of our invention.

In the drawing,

Figure l is a generally schematic showing of a physical, embodimentl of our invention,

Figures 2 to; 1l, inclusive, are vector diagrams illustrative of the use of our invention,

Figures 12` and I3 arev diagrams presented to assist in the understanding ofv the operation of our invention", andV Figure 14;' is a Wiringv diagram of electrical circuits involved in the practice of our invention.

Referring now to Figure i, it will be seenl that our invention comprises a triangular linkage it, the lengths of. Whose sides are indicated by the lines Il, I2 and I3. The lengths of these lines and' the angles by which. they arerelated are determined by knobs and' motor drives Which influence the linkage through various mechanical trains about to` be described.

It will be seen. that the invention comprises a shaft 23 mounted in suitable bearings, not shown. A bevel gear 2li is mounted on shaft 2:@ for unitary rotation therewith, as is4 the upper disk 22 of a slip friction mechanism 23. A worm wheel 2:3 is mounted" for iree rotation on shaft 2t; and is connected thereto by frictional` engagement with disk 2-2 through friction disk 25' oi mechanism Z3. A worm 32 is. carried' by the shaft 33 of a suitably mounted motor 34, and engages Worm Wheel 24 in driving relation. An electrical contact arm 26 isy mounted on a hub 28 of worin wheel 24, for unitary rotation therewith, by an insulating boss 2?. A circularresistance member 33 is mounted by any convenient means, not shown, for cooperation with member 25' as it rotates with worm Wheelf 2li' to comprise a variable resistor 29'. At its upper end shaft 29' carries a rack guide member 3l'.

A bevel gear 35 is carried by a shaft 36 l mounted in suitable bearings, not shown, and engages bevel gear 2l carried by shaft 23. Shaft 3 is rotatable by a manual knob 3i and carries a pointer 43 which cooperates with a suitably supported fixed scale 4l to indicate the amount of rotation of shaft 33. By this arrangement it -will be apparent that rotation of knob 3l acts to cause rotation of rack guide 3l around the axis of shaft 2t, and that energization of motor 34 acts in a similar fashion. Since reversel drive Y from worm wheel 24 throughworm 32 to motor 34 is impossible because of the mechanical nature of the drive, the interposition of slip friction member 23 is necessary in order to permit 3 drive of shaft 2B in either direction by knob 31: when the knob is turned, rotation of shaft 2li takes place, worm wheel 24 slipping with respect to upper disk 22.

Shaft 26 is hollow and is traversed by a second shaft 42, for which it forms a bearing. At its lower end shaft 42 carries a bevel gear 43 which meshes with a second bevel gear 44 carried by a second shaft 45. yShaft 45 is mounted in suitable bearings, not shown, and carries at its outer end a manual knob 4B.

At its upper end, shaft 42 protrudes beyond guide 3| and carries a gear 5| which meshes with a rack 52 carrying a pivot 55 at one end. Rack 52 is restrained between gear 5| and a shoulder portion 48 of guide 3|, and rotation of gear 5| with respect to guide 3| causes linear displacement of rack 52 along the guide. The shoulder portion 43 of guide 3| may carry a plurality of indicia 53, and rack 52 may be provided with an index 54 to indicate the displaced position of rack 52.

Shaft 42 is closely fitted within shaft 2li, so that when shaft 25 is rotated byknob 3l or motor 34, shaft 42 is carried with it, rotating knob 45. By this means manual or motor rotation of shaft 2D is prevented from changing the position of index 54 with respect to scale 53.

The effect of rotating knob 46 is to change the linear displacement between the axes of shaft 2li and pivot 55, and this distance comprises link i i. The end of the rack is offset so that for a zero indication of index 54 with respect to graduation 53 the axes of shaft 2li and pivot member 55 are colinear, and rotation of guide 3! about the of shaft 20 by knob 31 produces no change in the position of pivot member 55.

A second shaft 56 is mounted by any suitable means (not shown) for free rotative movement without axial movement. Shaft 55 carries an external thread l, cooperating with an internal thread 53 in a pivot member 6|, which accordingly is translated axially along the shaft as the latter rotates. On one end shaft 55 carries a gear l|52 which engages a plurality of gears 53 i and 64. Mounted on and insulated from gear (i3 is a contact member 65, and a circular resistor 56 is flxedly mounted in any suitable fashion (not shown) for sliding engagement by contact member 65, as the latter rotates, to comprise a variable resistor 68.

It will be appreciated that under some conditions rotation of shaft 55 through a number of revolutions may be required. ln such cases a gear reduction may be provided between shaft r 5B and variable resistor 58, or a helical variable resistor may be used.

Gear 54 is carried on the shaft 51 of a second suitably mounted motor l!) so that energization of motor ll) is effective to cause movement of pivot member 5| axially of shaft 55. It will be appreciated that motor 'lll may be replaced by a manually operated knob at the desire of the user,

and this is also true of motor 34.

A linear guide 1| is pivotally mounted upon pivot member 5| and is bored to slidingly re- 4 with contact member 13. It will now be apparent that rotation of shaft 56 from whatever cause is effective to vary the displacement between the pivot of pivot member 6| and the center of shaft 25, and this displacement comprises link i3.

Link |2 comprises the distance between the pivot of pivot member 5| and pivot member 55. This distance varies independently with movement of pivot member 6| along shaft 56, with displacement of pivot member 55 from the center of shaft 20, and with rotation of rack guide 3| about the axis of shaft 20. For each set of values of these variables, there is a single unique condition of rod 12 which is indicated by the length of link I2 and the angle between links |2 and |3, as illustrated in Figures 3 to 13, inclusive.

The operation of our invention is based on considerations illustrated in Figure 2.

When a body locatedy at B is subject to two forces acting in generally different directions, the resulting effect on the body can be represented by a single force acting in a single direction. Thus, if nBnl-5 is the vector representing the first of a pair of forces and 'l-3 is the vector representing thesecond force, there is a third vector BA which is representative of a single force having the same effect on the body as the two forces acting jointly. As is well known, vector B is obtained by setting the tail of one of the vectors at B, and placing the tail of the second vector on the head of the first, moving each vector always parallel to itself without changing its length. A vector drawn from the starting point to the head of the last vector is the vector sum of the vectors; that is, the single equivalent vector having the desired direction and magnitude. Thus, if the vector is laid out from point B and the vector :T255 1S moved so that n s tail is on point o, it will take the position OA. l-S- is therefore the sum of vectors B6 and B l Suppose that the force B15 changes its direction with respect to an arbitrary reference direi tion M, and takes a new direction B D, vector BO remaining unchanged. The vector triangle is now BOA instead of BOA and both the length of E' and the magnitude of angle BAO differ from BA and BAO. This is clearly not the same as rotating the whole triangle BAO about i ts vertex O until f3- takes a new direction OA', since the latter movement would displace B from its proper location. Reference will later be made to this distinction.

If the vector b6B (=-B O) is substituted for vector B it is possible to `start from O and lay olf the two vectors, joining their heads by vector .EA- as before. This method is of convenience, since it makes possible the determination of a point, O, which may be fixed in space and from `which both vectors may be laid oil: this method is used in the practice of our invention, and the vectors accordingly represent velocities.

Suppose the true air speed of an aircraft and also the wind velocity are known both in magnitude and direction. As far as the movement of the craft with respect to the earth is concerned, the two velocities represent the effect on the craft of two forces, the engines and the wind: the actual direction and speed of movement of the craft over the ground is the vector sum of these velocities as outlined above. The curvature of the earth may be neglected since the altitude of the craft is negligible in comparison with the s earths radius., 55.. the' center o! shaftsY andy 20; and the pivot ofl member tlE in.l'is1.ne lL correspond respectively to points. B., Q, and A in Figure 2.., Motors 34 and 1.3, resistance windings 3.1i and B6, the axial directions ofshafts 20,. 42,

and G., and so forth, form a matrix which is fixed with respect to. the craft,l and which cor-v responds to reference Ml in Figure 2. lili, and correspond to vectors ('--BOll BA and l Link I3 =Oll is varied in length by motor in accordance with the true air speed of the craft, as discussed below and is fixed with respect to the matrixl so that it bea-rsan unchanging relation to the headingoi` the craft: the link is ltherefore a vectory representative of the true air speed to an arbitraryl scale. In similar fashion, link I I. (f1-15) is a. vector representative of wind velocity tothe same scale: it is variable in length by knob 46 and its angle .with respect. to the matrix is adjustable bygknob 31.

Qn receiving the report as to the direction and speed of.- the wind at the desired altitude, or after making an 'estimate of these factors, it is only necessary to adjust knobs 31 and 416 until the required values are indicated by indices 54'. and 4U.. LinkA I'I then has the length and direc.

tion with respect, to link I'3 necessary for vectorially representing the wind on the same scale. Link, f2 is. accordingly lthe Vector sum of links II' and I3; its length isa measure of the ground speed to the same arbitrary scale, and its` angle with link I3 gives the drift angle of the craftthat is, the angle between the heading of the crait and its. ground path.`

From a study of Figure lL it is apparent that link I3 and shafts 201 and. 4.2 area. part of the matrix which is fixed to the craft, and' that the whole triangle is rotated in space when. the craft turns., As. pointed out. above, change in a vector produces a change. in they vector sum. which is not'the same as rotating the Whole triangle.: therefore, means are provided for changing the angular relation between links [I and [3. as. the matrix turns, so that the links properly represent vectorial'ly the forces involved'. Thus, if the craft is heading along a line parallel to shaft 56 as indicated by arrow 19 and turns to the left through ,y rack guide 3| must be. rotated through 15 in a counterclockwise direction to maintain the vectors. the proper angular rela.- tion. This function is performed, by azimuth motor 34 actingIl upon guide 3l through worm 32, worm wheel 24,. and friction drive 23:.. knob.. 3.1 is automatically rotated as motor 3.2 operates to vindicate the new angular relation. between wind and. heading of the craft..

Gears ZI' and 35 havethe same number or teeth, so that one rotation ofvknob 31 causes one rotation of guide 3'I`y .about the axis 'of shafts 20 and 42. Motor 34 i-senergized by a compass', as will be discussed belowyandi if the linvention is installed so that ind-'ex 4i' indicates zero when the heading of the eraf-tris north and the wind direction is. north, theangle indicated byJ index 4I for any other windfangle. setting' is the bearing of thewind, either geographically or magnetically, depending on the type` ofI eompassused. Since the bearing 0i: the matrix is fixed with respect to the craft, its directional bearing is always the heading of the craft: for all maneuvers.

Before discussing the means energizing motors 3,4 and 1U, and the functions of variable resistors 29, @8, 11, and 18, Figures 3 to. 1l should be noted.

These figures: illustrate typical vector triangles encountered, in the. use of our invention, and also the way in which the device, is applied to these problems'L Figure 3y is used as an arbitrary basis, and the remaining figures illustrate various alternative conditions which may be encountered.. In these figures, links I I, I 2, and I3 are identical, and poi-nts O, A, and Br are. also shown, corresponding with similar points in Figure 2 in their relation to. Figure L In each ligure the drift angle of the. craft is indicated by e and the upturned end 19 oi member 12 is indicated by C'.

In each of the figures link I3 is, angularly fixed with respect. to datum M, while link I I is capable of angular displacement with respect thereto. Both link Il and link` I3 are capable of linear adjustment from point O., and link I2, pivoted at point B, is free to. slide in bearing (il at point A so that its length 'A is the desired vector sum. The unused portion ofl member 12 extends beyond A in the direction The expressions same and changed are based on Figure 3.

In Figure 4 link I'I is extended while link I3 is the saine: A2B2 is greater than A1131 and a2 is. greater than a1.

In Figure, 5 link I'3 is reduced and link, i E is the same: AgBs is less than A131 but as is greater thi/lirici.

In Figure 6 link II is reduced and link I3 is extended: A4B4 is less. than A1B1, and a4 is less 'than al.

In Figure. 1' link Iv I. is the same and link i3 is reduced; link II is also rotated about O through 18.0? AsBs is less than .A1B1 and as: -a1=(360 In Figure 8 link I3 is the saine but link II has been reduced to zero'.- AGBs is .less than A1131 and 116:0. This is the condition of no wind.

In Figure 9 .link I3 is the same While link II has been reduced and rotated so that it lies along link I3 but. extends in the, opposite direction: A7137 is greater than A1131 and 05:0. This condition is, met with in direct headwinds.

In Figure. 10, link E3 is the same, but linkv I I has been reduced and rotated so that it. lies along` link I3 and extends in the same directiorn AsBe is less than A1131 and a,=.0. This is the condition in direct tail winds.

In Figure l1 links I and' i3 are unchanged, and link I I; is rotated through an arbitrary angle. A939 is greater than A1B1 and a9 is less than a1.

Figures 3 to ll have been presented to show that i'or each particular length, of link I3 and length and' angle of link |,I there is a singular combination oi length and angle of link I2 which corresponds Figures 12 and 1.3. compare the angles and the lengths respectively for the illustrated cases to make, this point more evident.

In Figure JA there. is. schematically shown a 'system including our invention, indicating methods by which motors. 3.-@ and l0- will` be energized and also showing means. for utilizing variable resistors, 'il'. and. I8, Our system is shown to cornprise a num-ber of' normally balanced electrical bridges, lili', lili, i623, and Hifi. energized from a common, source. itil, each bridge comprising a plurality oi impedance. arms which we here show as simple. resistance members.

Bridge 103, has; input terminals las and ist and output terminals. m1 and m8., and comprise iixed resistors. I I I and I.I2 and variable resistors H3 and 6d.. n mechanical input. mechanism iid controlled by a true air sneed meter schematically indicated at IIE is shown, as varying the resistance of resistor H3. Thisv unbalances bridge |03, impressing a signal voltage on an amplifier II 6 connected to the output of the bridge. Motor 10 is accordingly energized to operate in a forward or reverse direction depending upon the direction of unbalance of the bridge, and a mechanical link I I1 between motor 10 and resistor 68 enables operation of the motor to rebalance the bridge. The extent of movement of motor I is hence dependent upon the extent of deviation of the air speed as measured by airspeed meter I|5.

In Figure 1, link ||1 comprises shaft 61, gears 64, 62, and B3, and arm 65: gear 62 also moves member 3| along shaft 56. Operation of this bridge is effective to adjust the length of link I3 along shaft 5t in accordance with the indication of airspeed meter I I5. As previously pointed out, it may be desired to set the length of link I3 manually instead of automatically: in such a case bridge |03 can be omitted.

Bridge |04 has input terminals |35 and |36 v and output terminals |31 and |38, and comprises fixed resistors |2| and |22 and variable resistors |23 and 29. A mechanical input |24 from a magnetic or gyro compass |25 is shown as varying the resistance of resistor |23. This unbalances bridge |04, impressing a signal voltage on an amplifier |26 connected to the output of the bridge. A motor 34 is accordingly energized to operate in a forward or reverse direction, depending on the direction of unbalance of the bridge, and a mechanical link,|21 between motor 34 and resistor 29 enables operation of the motor to balance the bridge. The position of motor 34 hence will be dependent at all times upon the' heading of the craft as det-ermined by the compass |25.

In Figure 1 link |21 comprises shaft 33, Worm 32, worm wheel 24, hub 28, and slider 26. It will be apparent that due to the positive drive between worm 32 and worm wheel 24, no movement of slider 26 can take place except under the actuation of motor 34, and that no actuation of knob 31 has any effect on the relation between arm, 26 and winding 30.

While of course it is possible to continually adjust the angular relation of rack carrier 3| to shaft 56 by hand, in which case bridge |04 will not be required, itis much more convenient to provide the telemetric system controlled by the compass.

Bridge ID! is shown to comprise a plurality of fixed resistors |40, |4I, and |42 and the variable resistor 18, and has input terminals |43 and |84 and output terminals |85 and |85. A meter |91 of any suitable type is connected to the output terminals of the bridge Yto indicate the amount of the unbalance. In Figure 1 resistor 18 is shown as being adjusted in accordance with the drift angle a of the craft; that is, with the angle between shaft 55 and member 12. The scale of meter |91 can accordingly be graduated directly in units of drift angle if desired. Drift angles larger than in either direction can not ordinarily be anticipated, and a meter graduated 60 either side of dead ahead should -be suiiicient for any situation encountered by modern commercial craft: a scale range of 120 is easily to be obtained with available meters.

Bridge |02 is shown to comprise a plurality of fixed resistors |50, |5I, and |52 and variable resistor 11, and has input terminals |53 and |54 and output terminals |55 and |56. A meter |51 is connected to the output terminals of the bridge te indicate-the amountef the unbaia'nee.

In Figure 1, resistor 11 is 'shown as being adjusted in accordance'with the magnitude of link I2; that is, the vector sum of the air speed and wind velocity, or the ground speed of the craft. The scale of meter |51 can be graduated directly in units of speed if desired, and the compression of the high speed end of thescale, due to the load on the unbalanced bridge provided by the meter is not inconvenient, since the vlarger values of ground speed are less likely to occur, and'it is less necessary to read them with extreme accuracy. Operation of this bridge is effective to give an indication of the magnitude of the ground speed when the magnitude and direction of the air speed are known. It will be appreciated that if it is desired amplifiers and telemetric systems may be included in bridges |0| and |02 just as they were in bridges |03 and |04 to give remote indication of ground speed and drift angle, and it will also be appreciated that if desired members 12 and 6| can be graduated in linear and angular units respectively for direct mechanical reading of drift angle and ground speed without intervention of electrical means.

The operation of our invention may be summed up as follows.l -The device is mounted in the craft with the axis of shaft 56 extending fore and aft, and with guide 3| so arranged that when pivot 55 is in line with shaft 5 6 and between the shaft and the center of gear 5I, index 40 indicates zero on the scale 4|. Suppose now that the craft is flying due north at an air speed of 200 miles an hour. In response Vto ,the true air-speed meter, motor 10 is energized to move pivot member 6| along shaft 56 to a position corresponding to this air speed, and pivot 55 is coaxial with shaft 42. Now if the wind is estimated as 50 miles an hour, and its direction as easterly, knob 31 is rotated until it indicates or due east, which is the negative of the direction of the wind, and knob 46 is rotated until index 54 comes to rest at the graduation corresponding to 50 miles per hour. The triangle comprising links I I, I2, and I3 is accordingly set up to give an indication of the drift angle of the plane and its ground speed, the former being evidenced by indicator |91 and the latter by indicator 51 in accordance with the `unbalance of theY respective bridges due to movement of contact members 14 and 13, respectively.

If the heading of the craft now changes by operation of the rudder or due to some inadvertent cause, motor 34 is actuated to rotate worm wheel 24and with it shaft 20, rack guide 3|, and indicator 4|. Rotation of rack guide 3| changes the length and direction of link I2 to correspond with the new `heading of the craft and its new relation to the wind, and indicators |01 and |51 again show the ground speed and drift angle of the craft in its new direction of flight.

Numerous objects and advantages of my invention have been set forth in the foregoing description together with details of the structure and function of the invention, and the novel features thereof are pointed out in the appended claims. The disclosure, however, is illustrative only, and we may make changes in detail, especially in matter of shape, size andarrangement of parts, within the principle of the invention, to the ful1 extent indicated by the broad general meaning of the terms in which the appended claims are expressed..

9 l Weclaim as our invention: A

1. In a computer, in combination: a first memlber extending from a iixed point in a fixed direction; a second member; means varying the the magnitude of a second vector quantity, and.

means varying the directionr of said last named member relative to that of said first named member in accordance with the direction of said second vector quantity relative to that of said first vector quantity, so that the line joining said remote ends of said members is the resultant of said vector quantities; and a control member comprising a rst portion operatively connected to the remote end of one of said members and a second portion connected to the remote end of the other of said members and moveable with respect to said first portion; the control effect of said control member being determined by the distance between said first and second portions thereof'.

2. In a computer, in combination: a first member extending from a fixed point in a fixed direction; a second member; means varying the displacement. of the remote end of said first member from said point in accordance with the magnitude of a first vector quantity, means varying the displacement of the remote end of said second member from said point in accordance with the magnitude of a second vector quantity, and means varying the direction Vof said last named member relative to that of said first named member in accordance with the direction of said secend vector quantity relative to that of said first vector quantity, so that the line joining said remote ends of said members is the resultant of said vector quantities; a third member joining the remote ends of said members; a first. control member comprising a first portion operativeljT connected to the remote end of one of said members and a second portion fixed with respect to the remote end of the other of said members and movable with respect to said iirst portion, the control effect of said first control member being `determined by the distance between said first and second portions thereof; a second control member comprising a iirst portion located at said first named remote end and xed with respect to angular movement relative to the direction of said first member and a second portion angularly moveable with respect to said first portion in accordance with the direction of said third member with respect to that of said rst member; the control effect. of said second control member being determined by the angular displacement 'between the rst and second portions thereof;

a fourth member located at the remote end of said first named member and arranged for linear adjustment with respect to said third member and for rotational adjustment with respect to said rst member; and means mounting said second portions of said first and secondcontrol members upon said fourth member.

3. In a device of the class described, in combination, a pair of shafts, the axes of said shafts being mutually perpendicular, a first pivot member mounted for axial movement along one of said shafts, means for causing said axial movement, a second pivot member mounted for radial movement with respect to the other of said shafts and for rotative movement unitary therewith, means for causing said radial movement, of said second pivot member, means for causing rotative movement of said last named shaft about its axis, a guide pivoted about said first pivot member, a rod pivoted about said sec.- ond pivot member for slidingly engaging said guide, said axial movement, said radial movement, and said rotative movement causing angular movement between said guide and said first pivot member, said movements likewise causing sliding movement between said rod and said guide, electrical contacting members carried by said guide. and electrically insulated therefrom, an electrical resistance member cooperating with one of said contacting members for relative movement therebetween on angular movement of said guide with respect to said first pivot member, an electrical resistance member cooperating with another of said contacting members for relative movement therebetween on sliding movement of said guide with respect to said rod, means connecting said contacting members and said resistance members in electrical circuits whereby said relative movements may vary the resistances of portions of said circuits, and means deriving indications from said changes of resistances.

4. In a device of the classv described, in combination: a pair of shafts, the axes of said shafts being mutually perpendicular; a first pivot member mounted for axial movement along one of said shafts; means for causing said axial movement; a second pivot member mounted for radial movement. with respect. to the other of said shafts and for rotative movement unitary therewith; means for causing said radial movement of said second pivot member; means for causing rotative movement of said last namedshaft about its axis; a guide pivoted about. said nrst pivot member and a rod pivoted about said second pivot member for slidingly engaging said guide, said axial movement, said radial movement, and said rotative movement causing angular move.- ment between said guide and said first pivot member and sliding movement between said rod and said guide; and control means carried in part by said guide and in part. by said rod and said iirst pivot member for giving outputs re.- sponsive to said sliding movement and said angular movement.

5. In a device of the class described, in combination: a pair of shafts, the axes of said shafts being mutually perpendicular; a rst pivot meinber mounted for axial movement along one of said shafts; means for causing said axial movement; a second pivot member mounted for radial movement with respect to the other of said shafts and for rotative movement unitary therewith; means for causing said radial movement of said second pivot member; means for causing rotative movement of said last named shaft about its axis; a guide pivoted about said nrst pivot member and a rod pivoted about said second pivot member for slidingly engaging said guide, said axial movement, said radial movement and said rotative movement causing sliding movement between said guide and said rod; and control means carried in part by said guide and in part by said iirst pivoted member for giving an output responsive to said sliding movement.

6. In a device of the class described, in combination, a pair of shafts, the axes of said shafts being mutually perpendicular, a first pivot member mounted for axial movement along one of said shafts, means for causing said axial movement, a second pivot member mounted for radial movement withv respectv to theother of said shafts and for rotative movement unitary therev/ith,. means for causing said radial movement of said secondpivot member, means for causing rotative movement of said last named shaft about itsv axis, a guide pivoted about said -rst pivot member, a rod pivoted about said second pivot member for slidingly engaging said guide,A said axial movement, said radial movement,` and saidrotative movement causing anguiarmovement between said guide and said first pivot member, an electrical contacting member carried by said guide and electrically insulated therefrom, an electrical resistance member cooperating with said contacting member for relative movement therebetween on angular movement of said guide with respect to said first pivot member, means connecting said contacting member and said resistance member in an electrical circuit whereby said relative movements may vary the resistance of a portion of said circuit, and means deriving indications from said changes of resistance.

7. In a device of the class described, in combination, a pair of shafts, the axes of said shafts being mutually perpendicular, a first pivot member mounted for axial movement along one of said shafts, means for causing said axial movement, a second pivot member mounted for radial movementV with respect to the other of said shafts and for rotative movement unitary therewith, means for causing said radial movement of said second pivot member, means for causing rotative movement of said last named shaft about its axis, a guide pivoted about said first pivot member, a rod pivoted about said second pivot member for slidingly engaging said guide, said axial movement, said radial movement, and said rotative movement causing sliding movement between said guide and said iirst pivot member, an electrical contacting member carried by said guide and electrically insulated therefrom, an electrical resistance member cooperating with said contacting member for re'lative movement therebetween on sliding movement of said guide with respect to said rst pivot member, means connecting said contacting member and said resistance member in an electrical circuit whereby said relative movement may vary the resistance of a portion of' said circuit, and means deriving indications from said changes of. resistance.

8. In a wind triangle computer for use in avigation, in combination: means defining a position of zero displacement, means defining a zero of `direction from said first means; a first member of variable position defined by the magnitude of its displacement from said zero position along said direction; a second member of variable position defined by the magnitude of its displacement from said zero position and the magnitude of the angle between the zero direction and the direction of the line joining the position of said second member with said zero position, motor means for varying the displacement of said first member with variation in the air speed of a craft; means for relating the magnitude of the displacement of said second member with the magnitude of the wind encountered by said craft; manual means for relating said angle with the angle between the heading of the craft and the direction of said wind; means for maintaining ysaid relation unchanged regardless of change in the heading of the craft; vmeans linking said members, and means, including impedance means mounted on said linking means giving electrical response proportional to the effective length of said `linking means, said response being related to the magnitude of the velocity of the craft with respect to the ground beneath it.

9. In a wind triangle computer for use in avigation, in combination: first and second members rotatable about a common axis; a third member movable in a fixed direction, coordinated with the headingof a craft, with respect to said axis; motor means varying the distance between said member and said axis in response to variations in the'air speed of a craft; a wind velocity arm carrying a pivot at one of its ends; guiding and driving means carried by said first and second members for cooperation with said arm, whereby rotation of said first member varies the displacement of said pivot from said axis and rotation of said second member varies the angle between said fixed direction and the direction of said arm; manual means for rotating said first and second members through angles determined respectiveiy by the magnitude and the azimuth of the Velocity of wind encountered by said craft; motor means independently rotating said second member in response to change in the heading of said craft; means linking said pivot with said third member; first and second variable resistors; means varying the resistance of said first resistor with variation in the length of said link, and means varying the resistance of said second resistor with variation in the angle between said fixed direction and the direction of said link, whereby said resistances may be maintained in a given relation to the direction and magnitude f of the ground speed of the craft.

l0. An aircraft navigating instrument of the class described comprising, in combination, an axis, a first member displaceable from said axis in a fixed direction, a second member displaceable from said axis in any desired direction, a pair of electrical wipers carried by one of said members, a third member pivotally mounted upon said members and slidable in said one of said members, a linear resistance member carried by said third member for sliding contact with one of said wipers as said third member slides in said one member, and an arcuate resistance member mounted for'sliding contact with the other of said Wipers as said third member pivots about said one of said members.

11. An aircraft navigating instrument of the class described comprising, in combination, an axis, a first member displaceable from said axis in a fixed direction, a second member displaceable from said axis in any desired direction, an electrical wiper carried by one of said members, a third member pivotally mounted upon said members and slidable in said one of said members, and a linear resistance member carried by said third member for sliding contact with said wiper as said third member slides in said one of said members.

l2. An aircraft navigating instrument of the class described comprising, in combination, an axis, a rst member displaceable from said axis in a fixed direction, a second member displaceable from said axis in any desired direction, an electrical Wiper carried by one of said members, a third member pivotally mounted upon said members, and an arcuate resistance member mounted for sliding contact with said wiper as said third member pivots about said one of said members.

13. In a computer, in combination: a first member extending from a fixed point in a `fixed direction; a second member; means varying the the displacement of the remote end of said second member from said point in accordance with the magnitude of a second vector quantity, and

meansv varying the direction of said last named member relative to that of said rst named member in accordance with the direction ofv said second vector quantity relative to that of said iirst vector quantity, so that the line joining said remote ends of said members is the resultant of said vector quantities; a control member comprising an elongated portion and a'portion movable with respect thereto, the control eifect of said control member being determined by the position of said movable portion on` said elongated member; means aligning said elongated portion with the line joining said remote ends in a xedrelation to the remote end of one of said members; and means positioning said movable portion along said elongated portion inraccordance with the position of the remote end of the other of said members.

JOHN M. ANDERSON.

FRANK M. EXNER,.

RAYMOND E. HASELBERGER.

14 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,476,183 Roucka Dec. 4, 1923 1,743,239 Ross Jan. 14, 1930 1,784,929 Estoppey Dec. 16, 1930 1,910,093 Colvin May 23, 1933 1,968,539 Rydberg July 31, 1934 2,116,508 Colvin May 10, 1938 2,244,125 Siefker June 3, 1941 FOREIGN PATENTS Number Country Date 271,927 Great Britain May 30, 1927 392,827 Germany Mar. 25, 1924 463,251 France Dec. 12, 1913 571,074

Germany Feb. 23, 1933 

